Add date & datetime support to full_seq.

Fixes tidyverse#156

NAMESPACE

@@ -9,6 +9,9 @@ S3method(extract_,grouped_df)
 S3method(extract_,tbl_df)
 S3method(fill_,data.frame)
 S3method(fill_,grouped_df)
+S3method(full_seq,Date)
+S3method(full_seq,POSIXct)
+S3method(full_seq,numeric)
 S3method(gather_,data.frame)
 S3method(gather_,grouped_df)
 S3method(gather_,tbl_df)

NEWS.md

@@ -1,5 +1,7 @@
 # tidyr 0.4.1.9000
 
+* `full_seq()` now preserve attributes for dates and date/times (#156).
+
 * Sequences generated by `full_seq()` no now longer need to start at 0.
 
 * Moved in useful sample datasets from the DSR package.

R/seq.R

@@ -12,10 +12,31 @@
 #' @examples
 #' full_seq(c(1, 2, 4, 5, 10), 1)
 full_seq <- function(x, period, tol = 1e-6) {
+  UseMethod("full_seq")
+}
+
+#' @export
+full_seq.numeric <- function(x, period, tol = 1e-6) {
   rng <- range(x, na.rm = TRUE)
   if (any((x - rng[1]) %% period > tol)) {
     stop("`x` is not a regular sequence.", call. = FALSE)
   }
 
   seq(rng[1], rng[2], by = period)
 }
+
+#' @export
+full_seq.Date <- function(x, period, tol = 1e-6) {
+  restore(full_seq(as.numeric(x), period, tol), x)
+}
+
+#' @export
+full_seq.POSIXct <- function(x, period, tol = 1e-6) {
+  restore(full_seq(as.numeric(x), period, tol), x)
+}
+
+
+restore <- function(old, new) {
+  mostattributes(new) <- attributes(old)
+  new
+}

R/utils.R

@@ -73,3 +73,7 @@ regroup <- function(x, y, except) {
 # Allows tests to work with either dplyr 0.4 (which ignores value of
 # everything), and 0.5 which exports it as a proper function
 everything <- function(...) dplyr::everything(...)
+
+is_numeric <- function(x) {
+  typeof(x) %in% c("integer", "double")
+}

tests/testthat/test-full_seq.R

@@ -11,3 +11,11 @@ test_that("sequences don't have to start at zero", {
 test_that("full_seq fills in gaps", {
   expect_equal(full_seq(c(1, 3), 1), c(1, 2, 3))
 })
+
+test_that("preserves attributes", {
+  x1 <- as.Date("2001-01-01") + c(0, 2)
+  x2 <- as.POSIXct(x1)
+
+  expect_s3_class(full_seq(x1, 2), "Date")
+  expect_s3_class(full_seq(x2, 86400), c("POSIXct", "POSIXt"))
+})